DESCRIPTIONThe digest functions output the message digest of a supplied
file or files in hexadecimal form. They can also be used for digital
signing and verification. OPTIONS
-c print out the digest in two digit groups separated by colons,
only relevant if hex format output is used.
-d print out BIO debugging information.
-hex digest is to be output as a hex dump. This is the default
case for a "normal" digest as opposed to a digital signature.
-binary output the digest or signature in binary form.
-out filename filename to output to, or standard output by default.
-sign filename digitally sign the digest using the private key in "filename".
-verify filename verify the signature using the the public key in "filename".
The output is either "Verification OK" or "Verification Failure".
-prverify filename verify the signature using the the private key in "filename".
-signature filename the actual signature to verify.
-rand file(s) a file or files containing random data used to seed the random
number generator, or an EGD socket (see RAND_egd(3) ).
Multiple files can be specified separated by a OS-dependent character.
The separator is ; for MS-Windows, , for OpenVMS, and : for all
others.
file... file or files to digest. If no files are specified then standard
input is used.
NOTESThe digest of choice for all new applications is SHA1. Other
digests are however still widely used.
If you wish to sign or verify data using the DSA algorithm
then the dss1 digest must be used.
A source of random numbers is required for certain signing
algorithms, in particular DSA.
The signing and verify options should only be used if a single
file is being signed or verified.
HP Open Source Security for OpenVMS Volume 2:... 
OpenSSL Command Line Interface (CLI) Reference
